The invention relates to a method and device for displaying an autostereogram.
It is known to image a three dimensional scene by means of an autostereogram. This is described for example in PCT patent application WO 95/30968. An autostereogram is a two dimensional image in which a basic image pattern is periodically repeated along lines in a display plane which run parallel to an imaginary line connecting the intended positions of the eyes of a human viewer. In the autostereogram the spatial period of repetition is modulated dependent on variations in depth of surfaces from the scene both as a function of location along said lines running parallel to the imaginary lines and transverse to said direction.
To perceive depth from the autostereogram, the human viewer must make the lines of sight from his or her eyes to the autostereogram converge in a convergence plane different from the display plane in which the autostereogram is displayed. The distance between this convergence plane and the eyes of the human viewer corresponds to the distance at which an object of the three dimensional scene, for example a background, must be perceived. No three dimensional effect will perceived until the human viewer achieves convergence to the proper convergence plane associated with the autostereogram being viewed. This makes it difficult to perceive the three dimensional scene.